Various soil release agents which are effective on polyester are well known in the art. These are typically short chain polyesters and comprise a mixture of terephthalate residues and ethyleneoxy or propyleneoxy polymeric units. Such soil release agents are structurally similar to the polyester fabric, and thus, tend to build a protective film on the polyester fabric which enables easier cleaning. These soil release agents are much less effective on blends of polyester and cotton, and are completely ineffective on cotton. Generally, the majority of fabrics which require laundering are cotton or cotton blends. Hence there is a continuing need for soil release agents on cotton and cotton blends. An additional advantageous soil release agent would provide soil release benefits on polyester.
Styrene-maleic anhydride graft copolymers have been used in detergent compositions and cementitious mixtures. U.S. Pat. No. 3,485,762 describes a detergent composition containing an ammonium salt of a styrene-maleic anhydride resin and a non-ionic, hydroxyl containing surfactant. The nonionic surfactants and the styrene-maleic anhydride resins are present in the detergent composition as a physical mixture or as a partial ester of the nonionic hydroxyl-containing surfactant with styrene-maleic anhydride resin. Detergent compositions prepared with the styrene-maleic anhydride resin and nonionic surfactant are effective for cleaning hydrophobic substrates such as polyesters due to the hydrophobic nature of the nonionic, hydroxyl containing surfactant.
U.S. Pat. No. 5,158,996 describes a copolymer for use in a cementitious mixture. The copolymer is prepared by reacting styrene-maleic anhydride with a polyalkylene glycol. The copolymers act as a plasticizer and fluidifies cementitious mixtures. However, the use of such polymers in detergents has not been disclosed.